Phonograph record



Patented Mar. 17, 1953 fy vUNITED STATES PATENT OFFICE 2 Claims.

This invention relates to phonograph records, and particularly to those records of substantially disc shape, and a method for making the same.

In phonograph records, the most delicate portion is that area commonly designated as the sound groove area. This portion ordinarily occupies a large portion of the total area of the record. It is this portion which must be protected against injury, such as from scratches, nicks, and the like in order that the sound reproduction be as free as possible from extraneous and unwanted noise.

Heretofore the entire surfaces of the record have been substantially planar, the sound groove area forming a part of the friction surface by which the record is rotated. When the record is used in an automatic record changer or the like wherein the records are stacked one on the other, there is danger of damaging the sound groove areas when relative motion between the records occurs. Furthermore, there may be a danger in injuring the record through contact with a turntable.

It is accordingly one object of this invention to provide an improved form of phonograph record to reduce the hazard or" damage to the sound groove area. For this purpose, use is made of a phonograph record having a sound groove area of reduced thickness, as compared with other portions of the record. In this manner, the delicate area of the record is out of Contact with surfaces with which the record may contact, reducing the hazard of damage to the sound groove area.

In phonograph records it is always desirable to minimize the hazard of slippage while the record is in use. This is important in order that a constant angular velocity be obtained to insure an undistorted reproduction.

It is accordingly another object of this invention to provide a record that minimizes the hazard of undesired slippage of the record while it is in operation. For this purpose, the contacting surface by which the record is primarily rotated is concentrated at the outer p-eriphery thereof. In this manner any torque tending to cause slippage will be retarded by the frictional forces acting at substantially the largest lever arm obtainable.

It is still another object of this invention to provide a record that is sufficiently flexible to resist breakage during handling, but yet is sufficiently rigid to insure proper contact with the rotating surface during operation.

It is still another object of this invention to provide a phonograph record of this character that is simple in structure, but eiective in operation.

Still another object of this invention is to provide a record of this character in which the cost of manufacturing the record is substantially re-' duced, and parti-cularly by reducing the amount of material that is required to form a record of standard dimensions.

In phonograph records it is always desirable to have the starting spiral begin at the outwardmost porton of the record. In this invention, therefore, at least a part of the starting spiral will be located on the elevated rim portion of the record.

It is, therefore, another object of this invention to provide a record that has an elevated rim portion on which at least a part of the starting spiral is located, wherein the contour of the record is such that the cooperating needle is provided with a stable but steep downward traverse to the sound groove area. For this purpose, the tapered portion of the outer rim is slightly curved to provide a convex path for the needle.

It it still another object of this invention to provide a simple apparatus for making this iin-` proved record insuring an ample peripheral contacting surface together with a steep but smooth tapered portion leading to the sound grooves.

This invention possesses many other advan tages, and has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawings a-ccompanying and forming part of the present specification. The form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best deiined by the appended claims.

Referring to the drawings:

Figure l is a plan View of a record incorporating this invention;

Fig. 2 is a sectional view on an enlarged scale taken along the plane 2 2 of Fig. 1;

Fig. 3 is a fragmentary sectional View on a greatly enlarged scale showing the particular structure of a record incorporating this invention; and

Fig. 4 is a sectional View illustrating in particular the apparatus by which this record may be formed.

The record I0, generally of disc configuration,

comprises a sound groove portion II which may have sound grooves I Ia and I Ib respectively disposed on either side of the record. An outer annular rim portion I2 is shown as having starting spirals I2a and IZb respectively cooperating with the sound grooves IIa and IIb. An inner or central portion I3 has faces I3a and I3bV conventionally adapted to provide a surface upon which may be secured descriptive labels.

The inner portion I3 is suitably provided with an aperture Iii extending centrally thereof in order to permit the passage of a guiding spindle (not shown).

As shown most clearly in Figs. 2 and 3, the outer annular portion I2 is provided with substantially plane annular surfaces I5a and I5b on either side of the record l0. When it is desired to utilize the sound grooves IIa, the plane surface Ib is adapted to contact a rotating mechanism, such as a turntable.

Adjoining each of these plane surfaces I5a and i517 is a tapered annular surface Ia or Ib respectively terminating at the sound grooves IIa and IIb. The starting spirals I2a and I2!) traverse these tapered portions as it is preferred that the starting spiral be located on the out- Wardmost portion of the record. In order to insure stability of the needle on this downward traverse, the tapered portions Ia and Ib are shown as curved, the major portion thereof being convex so that there is but little tendency for the needle to jump the starting spiral I2a or I2b. The tapered portions IBa and 6b provide no discontinuities in slope between the pla-ne surfaces I5a and IED and the sound grooves i Ia and t I ib respectively.

These tapered surfaces converge toward each other in a radially inward direction, and thus the sound groove portion II is positioned intermediate the planes defined by the surfaces Ilia l and Ib. The surface of the sound groote portion II may be about ten one-thousandths of an inch inwardly of the planes defined by the surfaces Iia and I5b. The cross section of the record is thus of subtsantially channel shape, the sound groove portion Ii defining the bottom of the channel. By this structure, the sound groove il b will be out of contact with the surface by which the record IQ is rotated, protected from' possible harm. Similarly, the sound groove IIa will be protected from contact with other surfaces, such as when, in an automatic record player or the like, another record is placed on top of the record I5.

That part of the record generally designated as the sound groove portion ii includes eccentric grooves a and 25h respectively cooperating with the sound grooves I Ia and I Ib.

Tapered portions IIa and Ilb are similar to the portions Ia and Ib, and they lead from the innermost portion of the sound groove portion II and terminate at the Wider central portion I3.

The inner portion IS may assist the outer plane surface |51) in providing frictional stability, but the outer surface Ib being of considerable area and. being at a large distance from the center of the record I will exert the far greater stabilizing iniluence to prevent slippage of the record IS with respectrto the rotating surface.

In order to insure that the plane surface Iib contacts the rotating mechanism, the iiat face [3b lies slightly above the plane defined by the surface i517, as the thickness of the central portion I3 is less than that of the outer portion I2 at the plane surface portions. This does not necessarily prevent the face I3b from contacting the rotating surface, as the slight force exerted for instance, by the weight of the record or a contacting needle may flex the record IIJ so that face I3b becomes substantially coplanar with the surface I5b. The main purpose of the increased width of the central portion I3 as compared with the sound groove portion II is for stabilizing to a large degree the configuration of the record to insure that surface I5?) contacts the rotating surface. But this increased width of the inner portion I3 does not preclude substantial fleXure of the entire record; thus, the record is able to absorb shock in handling and thereby resist fracture.

The manner in which the record may be stamped to this desired configuration, is illustrated in Fig. 4. v

One of a pair of die members IS is shown upon which may be secured Athe thin copper stamper Is. The record may conventionally be formed by the die members being moved together, one oi' the record impressions being formed by the copper stamper I9 on plastic material that is placed between the stampers. The general structure of such apparatus is well known, but attention is here drawn to the particular mode oi supporting the stamper so that the improved record may be made.

A shim 2) lies between the die member I8 and the stamper IS. The peripheral flange portion 2i of the shim 2Q is of reduced thickness corresponding to the increased thickness of the rim portion or outer portion I2 of the record IIB. The shim' 2E! is provided with a tapered surface 22 of frusto-conical form corresponding to the tapered surface Ia or ISI) of the outer portion I2.

The stamper i9 is appropriately secured to the die member I3 to conform generally to the shape deiined by the shim 2t by the aid of a conventional clamp ring 23 suitably secured to the die member I3. The stamper will thereby be exed at its peripheral portions and suitably restrained from returning to its natural plane configuration.

In order to insure that the stamper I9 lies closely against the shoulder or flange portion 2 i, as well as the tapered surface 22, as pressure is exerted when the die members cocmrate to form' an impression, an annulairecess 2:3 is provided in the Vperipheral portion 2| of the shim 20 ad- `acent the base defined by the frusto-conical surace.

The stamper i9 will not assume exactly the frusto-conical shape o1" the tapered portion 22, but will be somewhat curved as indicated due to the natural tendency of therfiexible stamper I9 to assume a shape in which no slope discontinuities occur. The particular contour of the shim 20 pernits a rather steep taper of the desired configuraion.

The desired Vform of the record is thus achieved, there being a substantial flat portion Ia or I5b and `a convex tapered portion I 8a or Ib provided on the record.

It will be understood that the shim 2G may be made integral with the die member I8 and the same desired results achieved.

The inventor claims:

1. In a phonograph record of substantially disc configuration: an inner portion centrally disposed of the record; an outer portion; a soundw groove portion disposed between the outer and inner portions; the outer portion having fiat surfaces symmetrically disposed on either side of said record, said iiat surfaces defining two pargroove portion having a thickness less than that 16 of said inner and outer portions; the outer portion having a thickness greater than that of said inner portion, the entire record lying within two parallel planes defined by thevwidth of said peripheral outer portion, the outer portion having an area adequate to provide substantially sufficient frictional torque to eliminate slippage.

ALLAN R. ELLSWORTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 946,563 Rhodes Jan. 18, 1910 1,665,759 Vasselli Apr. 10, 1928 2,050,366 Moss Aug. 11, 1936 2,092,880 Hunter et al. Sept. 14, 1937 2,287,240 Haltenhof June 23, 1942 2,346,760 Kleber Apr. 18, 1944 2,503,609 Barnhart Apr. 11, 1950 FOREIGN PATENTS Number Country Date 124,508 Austria Sept. 25, 1931 561,809 Great Britain June 6, 1944 

